The Impact of BeamCal Performance at Different ILC Beam Parameters and Crossing Angles on \tilde{tau} searches

The ILC accelerator parameters and detector concepts are still under discussion in the world-wide community. As will be shown, the performance of the BeamCal, the calorimeter in the very forward area of the ILC detector, is very sensitive to the beam parameter and crossing angle choices. We propose here BeamCal designs for a small (0 or 2 mrad) and large (20 mrad) crossing angles and report about the veto performance study done. As illustration, the influence of several proposed beam parameter sets and crossing-angles on the signal to background ratio in the stau search is estimated for a particular realization of the super-symmetric model.Comment: Talk given by V. Drugakov at the Linear Collider Workshop "LCWS06'', 9-13 March 2006, I.I.Sc Bangalore, Indi

ECFA Detector R&D Panel, Review Report

Two special calorimeters are foreseen for the instrumentation of the very forward region of an ILC or CLIC detector; a luminometer (LumiCal) designed to measure the rate of low angle Bhabha scattering events with a precision better than 10$^{-3}$ at the ILC and 10$^{-2}$ at CLIC, and a low polar-angle calorimeter (BeamCal). The latter will be hit by a large amount of beamstrahlung remnants. The intensity and the spatial shape of these depositions will provide a fast luminosity estimate, as well as determination of beam parameters. The sensors of this calorimeter must be radiation-hard. Both devices will improve the e.m. hermeticity of the detector in the search for new particles. Finely segmented and very compact electromagnetic calorimeters will match these requirements. Due to the high occupancy, fast front-end electronics will be needed. Monte Carlo studies were performed to investigate the impact of beam-beam interactions and physics background processes on the luminosity measurement, and of beamstrahlung on the performance of BeamCal, as well as to optimise the design of both calorimeters. Dedicated sensors, front-end and ADC ASICs have been designed for the ILC and prototypes are available. Prototypes of sensor planes fully assembled with readout electronics have been studied in electron beams.Comment: 61 pages, 51 figure

Performance of fully instrumented detector planes of the forward calorimeter of a Linear Collider detector

Detector-plane prototypes of the very forward calorimetry of a future detector at an e+e- collider have been built and their performance was measured in an electron beam. The detector plane comprises silicon or GaAs pad sensors, dedicated front-end and ADC ASICs, and an FPGA for data concentration. Measurements of the signal-to-noise ratio and the response as a function of the position of the sensor are presented. A deconvolution method is successfully applied, and a comparison of the measured shower shape as a function of the absorber depth with a Monte-Carlo simulation is given.Comment: 25 pages, 32 figures, revised version following comments from referee

A precision luminometer for future linear collider experiments

The FCAL collaboration develops the technologies of compact and fast calorimeters to measure the luminosity at Linear Collider experiments both with high precision using small angle Bhabha scattering, and bunch-by-bunch using beamstrahlung pairs. Beside the luminosity measurement, the capability of detecting high energy electrons at low angles is important for many search experiments. A small Molière radius facilitates the measurement of Bhabha events in the presence of background and allows the detection of single high energy electrons on top of the widely spread background of beamstrahlung. A multi-plane prototype of a compact precision luminometer was studied in an electron beam with energies between 1 and 5 GeV at DESY. The results for the longitudinal and the transverse shower profiles are compared with Geant4 simulations of the setup. Very good agreement was obtained. The effective Molière radius of the prototype was determined. Again, very good agreement between data and Monte Carlo simulations was found. The value of the Molière radius approached the technological limit. A dedicated multi-channel ultra-low power readout ASIC is under development in 130 nm CMOS, comprising an analogue front-end and fast 10-bit ADC in each channel, followed by fast serialization and data transmission. In addition, an ASIC with a dual readout scheme allowing for a fast feedback to the accelerator and simultaneous data taking and calibration is under development. The paper summarizes the results on design optimization, beam-tests and the status of the readout ASICs

Compact LumiCal prototype tests for future e+e−e^+e^- colliders

The FCAL collaboration is preparing large-scale prototypes of special calorimeters to be used in the very forward region at future electron-positron colliders for instant luminosity measurement and a precise measurement of integrated luminosity and for assisting beam-tuning. LumiCal is designed as silicon-tungsten sandwich calorimeter with very thin sensor planes to keep the Molière radius small, thus facilitating the measurement of electron showers in the presence of background. Dedicated FE electronics has been developed to match the timing and dynamic range requirements. A partially instrumented prototype was investigated in a 1 to 5 GeV electron beam at the DESY II synchrotron. In the recent beam tests, a multi-plane compact prototype equipped with thin detector planes fully assembled with readout electronics were installed in 1 mm gaps between tungsten plates of one radiation length thickness. High statistics data were used to perform sensor alignment, and to measure the longitudinal and transversal shower development

Development and performance of a compact LumiCal prototype calorimeter for future linear collider experiments

The FCAL collaboration is preparing large-scale prototypes of special calorimeters to be used in the very forward region at future electron-positron colliders for a precise measurement of integrated luminosity and for instant luminosity measurement and assisting beam-tuning. LumiCal is designed as a silicon-tungsten sandwich calorimeter with very thin sensor planes to keep the Moli\`ere radius small, facilitating such the measurement of electron showers in the presence of background. Dedicated front-end electronics has been developed to match the timing and dynamic range requirements. A partially instrumented prototype was investigated in a 1 to 5 GeV electron beam at the DESY II synchrotron. In the recent beam tests, a multi-plane compact prototype was equipped with thin detector planes fully assembled with readout electronics and installed in 1 mm gaps between tungsten plates of one radiation length thickness. High statistics data were used to perform sensor alignment, and to measure the longitudinal and transversal shower development in the sandwich. This talk covers the latest status of the calorimeter prototype development and selected performance results, obtained in test beam measurements, the prospects for the upcoming DESY test beam, as well as the expected simulation performance